{
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular}{l*{4}{c}}
\hline\hline
                    &\multicolumn{1}{c}{\specialcell{\;\;\;\; Arsenic \\ contamination \\ \;\;\;\; (WHO \\ \;\; threshold)}}&\multicolumn{1}{c}{\specialcell{\;\;\;\;\;Arsenic \\ contamination \\ (Bangladeshi \\ \;\; threshold)}}&\multicolumn{1}{c}{\specialcell{\;\;\;\; Arsenic \\ contamination \\ \;\;\;\;\; level}}&\multicolumn{1}{c}{\specialcell{\;\;\;\;\;\; Fecal \\ contamination}}\\\cmidrule(lr){2-2}\cmidrule(lr){3-3}\cmidrule(lr){4-4}\cmidrule(lr){5-5}
                    &\multicolumn{1}{c}{(1)}   &\multicolumn{1}{c}{(2)}   &\multicolumn{1}{c}{(3)}   &\multicolumn{1}{c}{(4)}   \\
\hline
Treated             &      -0.022   &      -0.004   &       3.756   &       0.002   \\
                    &     (0.020)   &     (0.018)   &     (2.865)   &     (0.020)   \\
Constant            &      -0.096***&      -0.023   &       1.218   &      -0.033*  \\
                    &     (0.016)   &     (0.015)   &     (2.414)   &     (0.017)   \\
\hline
p-value (analytical)&        0.27   &        0.82   &        0.19   &        0.93   \\
p-value (RBI)       &        0.36   &        0.87   &        0.25   &        0.93   \\
Mean at baseline    &        0.62   &        0.24   &       28.97   &        0.65   \\
R$^2$               &        0.02   &        0.01   &        0.04   &        0.03   \\
N                   &        6051   &        6051   &        6051   &        6051   \\
\hline\hline
\end{tabular}
}
